In Patent Literature 1, there is disclosed a technology relating to a display device to be mounted on a vehicle, the display device “including: display means for displaying a message formed of characters, graphics, or images; visual line detection means for detecting a direction of a visual line of a user; and selection means for selecting, based on a detection result of the visual line, display means, to which the user is directing his or her visual line, as the display means for displaying the message from among a plurality of the display means”.